The present invention relates to a device for transferring and supporting panels, in particular printed circuit panels, and to the use of the device in an installation for exposing said panels to a source of radiation.
Printed circuit manufacture includes, in particular, a step of using various techniques to etch a deposit of copper made on one or two faces of an insulating panel so as to define the conductor tracks of the printed circuit.
Firstly, such panels can be of large dimensions, e.g. 610 mmxc3x97762 mm, whereas the present trend is for the thickness thereof to become smaller since they can commonly be as little as 50 xcexcm thick, and in exceptional circumstances as little as 5 xcexcm thick. It will be understood that handling such panels is difficult.
Secondly, when printed circuit panels are double-sided, it is necessary to etch them on both faces. When the etching step consists in exposing the panel to a light source through an artwork that defines the shape of the conductor tracks, it is possible to perform this operation simultaneously on both faces of the printed circuit panel.
New techniques for etching conductor tracks are presently becoming more popular, which techniques consist in replacing the operation of exposure through an artwork by an operation in which the layer of photosensitive material or xe2x80x9cresistxe2x80x9d deposited on the sheet of conductive material is treated by moving a laser beam, with the impact of the laser beam giving rise to local transformation of the resist layer making it possible, once the non-transformed portion of the resist layer has been removed, to etch the layer of conductive material. However, under such circumstances, it is not possible to perform this laser beam operation simultaneously on both faces of the printed circuit. It is therefore necessary to present each face of the panel in succession in the exposure machine.
In other techniques, the laser beam ablates the resist layer directly, or indeed no resist layer is used and the laser beam ablates the conductive layer directly.
It will also be understood that given the dimensions and the small thickness of such a panel, turning it over to enable both of its faces to be presented in succession in the machine raises great difficulties. Furthermore, it will be understood that a station for turning the panel over would lead to a significant increase in volume and thus in the overall bulk of the exposure machine as a whole once account is taken of the transfer means that would need to be associated therewith to make the operation entirely automatic, and that it would also lengthen the time required to perform the operations.
An object of the present invention is to provide a device for transferring and supporting double-sided panels, and in particular printed circuit panels, that enables each of the faces of the panel to be presented and positioned in succession in the exposure machine, while avoiding the drawbacks of a machine operating on the principle of turning the panel over.
To achieve this object, the invention provides a device for transferring and supporting a double-sided panel, in particular a printed circuit panel, the device comprising:
a bottom slab having a top reference surface that is plane and horizontal for receiving the bottom face of said panel;
a top slab having a bottom reference surface that is plane and horizontal for receiving the top face of said panel; and
displacement means for moving said slabs separately in two respective horizontal planes;
each of said slabs being provided with non-mechanical holder means that are controllable for pressing one face of said panel against the reference surface of said slab, when the holder means are activated;
said device further comprising controllable lifting means for controlling said panel, said lifting means not projecting from the reference surface of a slab when they are in a non-activated state, and being suitable for pressing said panel against the reference surface of said top slab when they are activated.
It will be understood that because of the presence of the top and bottom slabs, each face of the panel can be inserted into the exposure machine while maintaining very precise positioning of the panel in the vertical direction. The reference surfaces of each of the panels can be machined with very great precision and this positioning in the vertical direction is maintained because the panels are merely displaced in a horizontal direction.
In a preferred embodiment, the holder means are suction micro-nozzles opening out in the reference surface of said slab and regularly distributed over said surface.
Also preferably, the lifting means are micro-actuators disposed regularly in the reference surface of said bottom slab, each micro-actuator having a moving rod that moves in a direction orthogonal to the reference surface, said rods when in the non-activated position being completely withdrawn relative to said reference surface.
By using suction micro-nozzles and lifting micro-actuators, firstly the panel can be kept plane even if it is very thin, and secondly the panel can be transferred from one slab to the other slab without any risk of imparting localized deformation to the panel, since that would be incompatible with the type of treatment it is to receive.
Another object of the invention is to provide an installation for exposing a double-sided printed circuit panel to a source of radiation, which installation makes use of the above-defined transfer and support device.